The present invention relates to a separate read/write magnetic head for use in a magnetic disk device.
In order to meet the demand for greater capacity in magnetic disk devices, recording density has been increased over the years. There has also been a demand for smaller and high-speed magnetic disk devices. In order to satisfy the demands, a GMR (Giant Magnetoresistive) film is used in currently available magnetic disk devices as a magnetoresistive film of a separate read/write magnetic head, so that the recording track width is reduced to 0.4 μm and a gap (hereinafter referred to as flying height) between the magnetic head and a recording medium is reduced to about 15 nm.
The reduction in flying height of the head is essential for the achievement of high-density recording. However, the reduction in flying height may entail a problem of deformation of the head. Since the thin film magnetic head element is constituted of a plurality of components that differ from each other in thermodynamic property such as a coefficient of linear expansion, the head element is subjected to heat deformation that is caused by changes in ambient temperature. A partial protrusion is generated on the air bearing surface of the thin film magnetic head that faces the recording medium due to heat deformation, and the protrusion may make contact with the recording medium and therefore damage the magnetic head element.
FIG. 7 illustrates the configuration of a conventional separate read/write magnetic head 1 wherein an upper shield and a lower pole piece is separated from each other by a separation film that is an insulator. A GMR read head 2 has an upper shield 28 and a lower shield film 23 for eliminating magnetic fields brought by signals other than a desired signal, a GMR film 25 for detecting the desired signal, electrodes 26 for feeding a current to the GMR film 25, an upper gap film 27, a lower gap film 24, and the like. An inductive thin film magnetic write head 3 has a lower pole piece 31 and an upper pole piece 35 for generating a recording magnetic field, a magnetic gap film 32, coils 33 for applying a signal current, an interlayer insulating film 34, and the like. These films constituting the head 1 are formed on an insulating film 22 that is laminated on a substrate 21. Further, the overall head element is covered with a protecting film 36.
Japanese Patent Laid-open No. 2000-306215 (pages 4 to 6, and FIGS. 1 to 3 and 6) discloses a method of preventing an air bearing surface from being deformed during operation by forming at least an upper insulating layer (insulating interlayer) of an inductive magnetic thin film head from a resin having a low glass transition point of 70 to 100° C., a porous material, and polyimide to reduce heat deformation when high humidity is present or by polishing the air bearing surface of the head at a temperature as high as that generated during operation.